Bicycles have been used for recreation, transportation, and sporting competition for decades, and can be found in all types of environments (e.g., urban, suburban, and rural). What started out as a relatively simple assembly of components has evolved into more complex forms as bicycles have been adapted from general use (e.g., transportation, exercise) to more specific niches (e.g., Olympic-style track racing, BMX-style racing, cross-country cycling, etc.).
As bicycle use has changed, the cycling industry has adapted and improved various components of the bicycle in order to meet the evolving needs of the cycling public. A bicycle rear derailleur is one such component. The purpose of a rear derailleur is to assist in changing the speed of a bicycle by selectively moving a bicycle chain between gears of a cassette located near a rear wheel of the bicycle. A typical rear derailleur has a base member connected to the bicycle near the rear wheel, a chain cage (or chain guide) engaging the bicycle chain, and a movable member connecting the base member and the chain cage so as to move the chain guide laterally relative to the base member. Movement of the chain cage moves the bicycle chain between the gears of the gear cassette. A rider is able to shift gears due to a shift control device (or shifter) mounted on or near the bicycle's handlebar. One end of a control cable running down the length of the bicycle is connected to the shift control device and the other end of the control cable is connected the rear derailleur. The shift control device adjusts the amount of tension on the control cable. The shift control device allows the rider to pull (increase tension) or release (decrease tension) the control cable. An increase or decrease in tension on the control cable determines the direction on the gear cassette in which the bicycle chain moves (i.e., from lower gear to higher gear or from higher gear to lower gear). Increasing tension on the control cable causes the chain cage to laterally move in one direction relative to the base member (which, in turn, moves the bicycle chain in that same direction), while releasing tension on the control cable causes the chain cage to laterally move in another direction relative to the base member (generally the opposite direction the chain cage moves in when tension is increased). Thus, the chain cage (and bicycle chain) can be moved laterally by increasing or decreasing tension on the control cable.
During use, a bicycle can be ridden over a variety of surfaces and terrains including, without limitation, smooth surfaces (e.g., paved surfaces), rough surfaces (e.g., dirt roads, off-road terrain), and the like that can subject the bicycle to various conditions including, without limitation, bouncing, vibration, and the like. There may be hazards including, without limitation, potholes, rocks, and the like. These various conditions and hazards can impact the bicycle in various ways including, without limitation, causing a bicycle rider to crash, causing the bicycle chain to become disengaged from the gear cassette, causing the control cable to become disconnected from the rear derailleur, or the like. For example, when the bicycle is moving on a rough surface, uncontrolled movement of the chain cage can result in the chain cage moving back and forth between the direction of chain tensioning and in the opposite direction. This can result in the bicycle chain bouncing to the extent the bicycle chain becomes disengaged from the chain cage and/or the gear cassette.
Different types of rear derailleurs have been proposed that can move a bicycle chain between gears of a cassette. However, such rear derailleurs have their limitations and can always be improved.
Accordingly, there is a need for an improved rear derailleur that can move a bicycle chain between gears of a cassette. There is also a need for a rear derailleur that can mitigate the effects of various conditions and hazards that can impact engagement of the bicycle chain and the rear derailleur. There is an additional need for a rear derailleur that is easier to manufacture, assemble, adjust, and maintain. The present invention satisfies these needs and provides other related advantages.